Self-supporting shield system for portable blast/ballistic protection

ABSTRACT

A self-supporting shield system for portable blast and ballistic protection includes at least two large shields pivotally joined together at the top, or two rigid frames pivotally joined together at the top, each framed fitted with a number of armor plates. The two shields or two frames can be separated apart by pivoting around the joint to form triangular shape that is self-supporting and free standing. The shield system not only provides the self-supporting function under dynamic loading, but also increases energy dissipation of the projectile and enhance the reliability and survivability of the shield system.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to portable armor/shield systems to provide protections against projectile penetration and blast.

Description of Related Art

Armor or shield systems have two major forms: 1) large vehicle armor such as tanks, and 2) personal armor such as small body armor and helmets. Therefore, there is a significant size gap between these two kinds of armor systems. In urban warfare, soldiers leave large armored vehicles and enter houses or buildings. Their small body armor and helmets are hard to stop rifle shootings or blast, and the protection areas are small compared to their whole bodies. For example, injuries in their legs without armor protection will be serious in urban warfare which requires agile action. So, an intermediate armor/shield system would be helpful for combat.

In recent years, civilian and military targets are often under terror attacks worldwide, so armor/shield systems are needed to protect personnel and infrastructures. Since terror attacks are often random, portable protection is desirable.

SUMMARY

Embodiments of the present invention provide a simple yet effective shield design, such that the shield system not only provides a self-supporting function, but also increases energy dissipation of the projectile and enhance the reliability and survivability of the shield system. The technology in embodiments of this invention is more efficient than the existing technology (e.g. a single shield, tank or body armor). Military personnel, police and security guards may use this invention. The benefits for the users include 1) lightweights, 2) easy installation, and 3) multiple protection functions. For example, the shield system according to embodiments of the present invention may be quickly moved from an airport to a governmental building as needed. Unlike traditional shields which are held by the users, the shield systems according to embodiments of the present invention are self-supporting. Meanwhile, the shield system can be moved easily because of its portable function. Because one shield may not be easily self-supporting, at least two shields or a shield system may be employed to realize the self-supporting function. A main purpose of this shield system development is to protect military personnel, police and security guards.

In one aspect, the present invention provides a self-supporting and portable shield system for protection against blast and ballistic, which includes: a first plate shaped shield; a second plate shaped shield; a joint configured to pivotally join the first and second shields to each other at an edge of the first shield and an edge of the second shield; and a connection bar configured to detachably connect the first and second shields to each other at locations different from locations of the joint; wherein each shield is made of materials having blast and/or ballistic resistance properties, and wherein each shield has a height of 1.7 to 2.0 meters and a width of up to 0.4 meter.

In another aspect, the present invention provides a self-supporting and portable shield system for protection against blast and ballistic, which includes: a first rigid support frame;

one or more armor plates mounted in the first support frame; a second rigid support frame; one or more armor plates mounted in the second support frame; a joint configured to pivotally join the first and second support frames to each other at an edge of the first support frame and an edge of the second support frame; and a connection bar configured to detachably connect the first and second support frames to each other at locations different from locations of the joint; wherein each armor plate is made of materials having blast and/or ballistic resistance properties, and wherein each support frame has a height of 1.7 to 2.0 meters and a width of up to 0.4 meter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a self-supporting shield system according to an embodiment of the present invention, with at least two shields (1 and 2) jointed at their top (7) connected with a connection bar (3) against an explosion (5) or a projectile impact (6). A sandbag or other weights (4) may be optionally used in order to keep balance during an explosion.

FIG. 2A shows a cross-sectional view of the two shields in contact (1 and 2) subjected to projectile penetration (6A), and the projectile path (8A) is perpendicular to the shield surface.

FIG. 2B shows a cross-sectional view of two inclined shields (joint angle 2θ) jointed at their top (7) subjected to projectile penetration (6B), and the projectile path (8B) has an inclined angle with respect to the shield surface.

FIG. 3 shows a force and momentum analysis of the shield system with two shields according to an embodiment of the present invention.

FIG. 4 shows a shield protection system with an aluminum frame and several small armor plates (black) according to another embodiment of the present invention.

FIG. 5 shows a shield protection system with a smaller aluminum frame and several small armor plates (black) according to another embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

TABLE I (Identification of Parts and Components) Reference Numeral Name of Part 1 First shield which directly faces the threat 2 Second shield behind the first shield 3 Third shield or connection bar to connect the first and the second shields 4 Sandbag or other weights acting on the first shield 5 An explosion 6 A flying projectile such as a bullet 7 Joint of two shields 8 A projectile path 9 A large shield holder 10 An open window for shootings

FIG. 1 shows a basic unit of a self-supporting shield system according to an embodiment of the present invention. The shield system has at least two large shields (1 and 2) with blast and/or ballistic resistance pivotally jointed at their top by a suitable joint (7). The joint may be, for example, a hinge, which allows the two shields to pivot with respect to each other. The two shields are rigid, and a connection bar (3) is employed to connect the two shields at locations different from the joint (7) when the two shields are placed in inclined positions (i.e. they are pivoted apart from each other), so the shield system forms a triangular shape and is self-supported (i.e. and free standing) on the ground or other surfaces such as a ship deck.

In some embodiments, the connection bar (3) is a rigid bar having one end attached to (detachably or non-detachably) one of the shields, and another end attached to (detachably or non-detachably) the other one of the shields. For example, one end of the bar may be non-detachably and pivotally attached to one shield, and the other shield has a retaining structure (e.g. a loop or a post) to detachably retain another part of the bar. For example, a hook or a notch may be provided at the other end of the bar to engage the retaining structure of the other shield. The connection bar may also have multiple notches or holes along its length, where each notch or hole may be used to connect the bar to the other one of the two shields, so as to adjust the effective length of the bar (i.e. the length of the bar located between the two shields) and therefore the joint angle (i.e. separation angle) between the two shields. In some other embodiments, the connection bar (3) is formed of two pivotally connected rigid segments, and the two ends of the bar are non-detachably attached to the two shields. The two segments of the bar may be folded toward each other so that the two shields are folded toward each other, or the two segments of the bar may be extended so that the two shields are spread apart from each other. In some other embodiments, the connection bar (3) is formed of two rigid segments, each non-detachably and pivotally attached to one of the shields, and the two segments are provided with connecting structures to detachably connect them to each other. As discussed later, when the shield system is in use in the free standing configuration, the separation angle between the two shields (1 and 2) is preferably 10° to 90°, and more preferably 50° to 70°. To this end, the effective length of the connection bar (3) and its attachment locations on the first and second shields are designed to maintain such a separation angle. Those skilled in the art can easily determine these geometric parameters.

The shield system can have at least one sandbag or other weights (4) to prevent rotation during an explosion (5) or projectile impact (6). The size of the shield system may be determined by the protected targets behind the shield system. Usually, if the shield system is employed to protect a person, the height of the system is preferably 1.7-2.0 meters, which is higher than an average height of an adult. Therefore, each shield can cover an adult. The shield system is much larger than body armor and helmets, but it is smaller than an armored vehicle in terms of the total protection area.

Each one of the shields 1 and 2 is a plate shaped member having blast and/or ballistic resistance properties, and may be made of any suitable materials such as steel or other metal, a multi-layered structure with multiple layers of materials, etc. An example of a structure suitable for a shield is described in commonly owned U.S. Pat. Appl. Pub. No. 201/60169633, the disclosure of which is incorporated herein by reference in its entirety. The layered structure includes a first layer made of a first material, a second layer made of a second material, the second layer being an outer layer subjected to external loading, and a third layer made of a third material, where the first layer is located between the second and third layers and in contact with the second and third layers, and where an impedance mismatch between the first and second materials is greater than 60%, or a shear modulus mismatch between the first and second materials is greater than 60%. The first layer may be an adhesive that bonds the second and third layers together. the second material and the third material may be the same materials or different materials. The second material may be Homalite™-100, Plexiglas, polycarbonate or Kevlar™ fabric. The first material may be Loctite™ 5083 adhesive or silicone-rubber. Another example of a multi-layered protection armor structure suitable for a shield is described in commonly owned U.S. patent application Ser. No. 16/257,030, the disclosure of which is incorporated herein by reference in its entirety.

FIG. 2A shows a cross-sectional view of the two shields (1 and 2) when they are placed parallel to and in direct contact against each other, subjected to projectile penetration (6A), with a projectile path (8A) which is perpendicular to the shields' surfaces. A key parameter is the thicknesses of the shields “d”. This is a baseline shield configuration and the system has the least energy dissipation. In actual applications, the two shields of a shield system can be different and have different thicknesses, although FIG. 2A shows a shield system with two identical shields.

FIG. 2B shows a cross-sectional view of the shield system when the two shields (which are of equal heights in this example) are inclined relative to each other (with a joint angle 2θ) and are jointed at their top by the joint (7). Also, one connection bar (3) between the top joint (7) and the feet of the shields is employed to change the joint angle and to ensure the self-supporting function. In this illustration, the shield system is subjected to projectile penetration (6B), and the projectile path (8B) has an inclined angle (i.e. not perpendicular) with respect to the shields surfaces. Therefore, the projectile penetration distance of each shield of the shield system is D≈d/sin θ. If θ>0-degree, D>d. So, when the projectile penetrates these shields, it will travel a longer distance and dissipate more energy (product of force and its acting distance) than the straight shield combination illustrated in FIG. 2A. As a result, the projectile has less kinetic energy to completely penetrate the shield system. Therefore, this inclined placement of the shield system has improved reliability and survivability.

FIG. 3 shows a force and momentum analysis of one shield system with two different shields which are subjected to blast loading. Usually, a rifle bullet leads to much smaller impact force on the shield system than a blast or explosion. FIG. 3 shows analysis of the shield system subjected to blast loading (or sudden pressure). In this example, two shields (AC and EC) are joined at point C, and each shield is simplified as a line without any shape in this side view. The joint angle of two shields is θ_(B)+θ_(D) where θ_(B) and θ_(D) are the respective angles of the shields relative to the vertical direction CO. The two shields have different heights in this example (so θ_(B) is different from θ_(D)), but they may also have identical heights (in which case θ_(B) equals θ_(D)).

The lower ends (or feet A and E) of two shields contact a horizontal surface (e.g., ground) and the line CO (which equals to height of the shield system when the two shields are pivoted apart) is perpendicular to the horizontal surface. It should be noticed that due to the portable nature of the shield system, usually reaction force, not reaction momentum exits at the foot of each shield. The horizontal surface is assumed to be a rough, not smooth surface, so the horizontal component of the reaction force at each shield foot is not zero.

The shield system is designed to keep the whole shield system in an equilibrium state, when the system is subjected to high and sudden dynamic loading such as a blast. Blast loading is assumed to be uniform sudden pressure from the right side of the shield system shown in FIG. 3, and it will be further simplified as a concentrated loading acting at the center of each shield. Therefore, P_(B) is the concentrated force acting at the center B of the right shield, and P_(D) is the concentrated force acting at the center D of the left shield. The gravity acting on the right and left shields W_(B) (>0) and W_(D) (>0) are also at the shield centers.

In addition to the shield's weight to maintain a stable shield system, an external weight (e.g., a sandbag) can be added at the foot of the right shield (or each shield) in order to prevent the shield system's rotation or movement. As shown in FIG. 3, F_(AX) and F_(AY) are the reaction force components along the X and Y directions at point A, F_(EX) and F_(EY) are the reaction force components along the X and Y direction at point E. The driving force, or dynamic pressure P_(B) and P_(D) lead to the reaction force at points A and E. Usually P_(B)>P_(D)>0, or P_(D)=k P_(B) and k is a pressure ratio (0<k<1).

If the shield system has no rotation or movement, force balance along the X and Y directions can be expressed by:

ΣFx=F _(AX) +F _(EX) −S _(B) P _(B) cos θ_(B) −S _(D) P _(D) cos θ_(D)=0  (1)

ΣFy=F _(AY) +F _(EY) −W _(A) −W _(B) −W _(D) −S _(B) P _(B) sin θ_(B) −S _(D) P _(D) sin θ_(D)=0  (2)

where S_(B) and S_(D) are the total areas of two shields. According to momentum balance at point E,

ΣM _(E) =F _(AY)(2L _(AC) sin θ_(B)+2L _(CE) sin θ_(D))−W _(A)(2L _(AC) sin θ_(B)+2L _(CE) sin θ_(D))−L _(CE) sin θ_(D) W _(D)−(2L _(CE) sin θ_(D) +L _(AC) sin θ_(B))W _(B) +S _(D) P _(D) L _(CE) +S _(B) P _(B)[2L _(CE) cos(θ_(B)+θ_(D))−L _(AC)]=0  (3)

For a common symmetric shield system, L_(CE)=L_(AC)=L, θ_(B)=θ_(D)=θ, so the reaction force at point A along the Y-direction can be determined by equation (3),

F _(AY) =W _(A)+0.25W _(D)+0.75W _(B) −S _(B) P _(B)(2 cos 2θ−1+k)/sin θ.  (4)

Point A is the key point to examine the system equilibrium state during dynamic loading. A positive F_(AY) means that the shield is still in contact with the horizontal supporting surface (positive F_(AY) implies that the internal force is compressive). A negative F_(AY) means that the horizontal supporting surface and the shield's foot separates. If one ignores the factors of 1) the joint angle of two shields, and 2) the blast pressure P_(B) as seen in equation (4), one finds that the weigh contributions for the system balance are not equal. The external weight at point A makes 100% contribution for the reaction force F_(AY), but the weights of two shields make less contribution (25% and 75% of their weights). Therefore, adding sandbags and other external weights are more effective to keep the system's equilibrium state than increasing the weight of each shield. This is an important design principle, because the weight of the shield system can be reduced while the shield system's balance is mainly controlled by the external weight. Such a light shield system is more agile in combat. For example, a shield system made of very light Ultra-high-molecular-weight polyethylene (UHMWPE) ballistic fabrics (plus external steel weights) has the same protection functions as a steel shield system which is very heavy. The UHMWPE shield system can be moved easily, after the external weight is removed.

In terms of the joint angle design, there are two extreme cases, i.e., k=0 and 1. If the joint angles 2θ are 60° and 90°, (2 cos 2θ−1+k)/sin θ=0, or F_(AY)>0 in equation (4). Therefore, for a symmetric shield system with a large joint angle (from 60° to 90°), the shield system is stable for various kinds of shield shapes, cross-sectional areas or materials. Since P_(B) is the major driving force, the reaction forces are independent of the blast pressure for the above specific joint angles. The reaction force at point E along the Y-direction can be determined by equation (2),

$\begin{matrix} {F_{EY} = {{0.75W_{D}} + {0.25W_{B}} + \frac{S_{B}{P_{B}\left( {{2\cos \; 2\theta} - 1 + k} \right)}}{\sin \; \theta} + {S_{B}{P_{B}\left( {\left( {1 + k} \right)\sin \; \theta} \right)}}}} & (5) \end{matrix}$

Therefore, the weight at point A has no influence on the reaction force at point E. Also, for a practical shield joint angle, 10°<2θ<90°, F_(EY) is always greater than zero (stable). So the shield system design should be focused on point A which faces dynamic loading directly.

Examples

FIG. 4 shows an example of a shield protection system with two shields, preferably identical in size and construction. Each shield has an rigid support frame (11) made of a strong material such as aluminum or other metal or a fibrous composite, and several armor plates (12) mounted in the support frame. Each support frame defines a plane and the armor plates are disposed parallel to the plane. Preferably, each frame includes one or more horizontal rungs that divide the frame into two or more sections, and each armor plate is located in one of the sections. The functions of the support frame are 1) assembling and supporting small armor plates, 2) transferring dynamic loading from these armor plates to ground. The support frame (11) should have enough stiffness, strength and sizes to carry and transfer very high dynamic loading. The armor plates (12) have blast and/or ballistic resistance properties, and may be made of materials similar to the shields (1 and 2) in earlier described embodiments. The blast and/or ballistic resistance of the shield system is mainly provided by these armor plates, not the support frame. One advantage of using several small armor plates is that a small armor plate can be replaced easily if it is damaged. Indeed, a large shield/armor plate without any support frame can be employed in the shield system. However, a disadvantage is that, if the large shield has one damage (e.g., one bullet penetration), the whole shield must be replaced, so the total cost will be high.

Each shield in FIG. 4 can cover an adult against blast/ballistic threats, because the shield height is approximately 2.0 meters, the shield width is up to approximately 0.4 meter. The total weight of the shield system including the two identical shields with all armor plates is approximately 45 kg, which is not heavy for a solider or police officer to move around. A sandbag (4) is used to provide enough resistance for the shield to face blast. For this purpose, the support frame (11) has a horizontal base rung located near its feet on which the sandbag or other weight may be placed. The weight of the sandbag can be estimated from equation (4) if the threat level is known. The two shields were connected by a joint (7), such as two hinges, at the top. The whole shield system can be disassembled quickly into two large shields for two users. To this end, the joint (7) is removably attached to either or both of the two shields, or the joint may employ two parts that can be assembled together or disassembled. Each large shield has at least one shield holder (9) for the user to hold and move the shield. A small window (10) between some of the armor plates (12) may be provided for accurate shootings and observation by the user. This design is helpful for a solider or police officer to move, search and shoot quickly, while he or she is completely protected by the large shield system.

FIG. 5 shows another example of a smaller shield protection system with two identical shields. This shield system has a similar structure as the one shown in FIG. 4 and the same reference symbols are used. Each shield has an aluminum frame and several small armor plates. The shield height is 1.8 meter, the shield width=0.35 meter. The total weight with all armor plates=36 kg. The above two shield systems have the same protection levels, because they have the same armor plates. However, the shield system shown in FIG. 5 is light, because of its small aluminum frame. In this example, the frame 11 is provided with a lower gun supporter (13), which is a rod protruding horizontally form the frame where a gun may be placed. The shield system shown in FIG. 5 is effective for protection against AK-47 shootings and small bombs.

It will be apparent to those skilled in the art that various modification and variations can be made in the shield system of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover modifications and variations that come within the scope of the appended claims and their equivalents. 

What is claimed is:
 1. A self-supporting and portable shield system for protection against blast and ballistic, comprising: a first plate shaped shield; a second plate shaped shield; a joint configured to pivotally join the first and second shields to each other at an edge of the first shield and an edge of the second shield; and a connection bar configured to detachably connect the first and second shields to each other at locations different from locations of the joint; wherein each shield is made of materials having blast and/or ballistic resistance properties, and wherein each shield has a height of 1.7 to 2.0 meters and a width of up to 0.4 meter.
 2. The shield system of claim 1, wherein the joint is removably attached to either or both of the first and second shields, or the joint includes two parts are assembled together.
 3. The shield system of claim 1, wherein the connection bar is configured to maintain a separation angle between the first and second shields of 10° to 90°.
 4. The shield system of claim 1, wherein the connection bar is configured to maintain a separation angle between the first and second shields of 50° to 70°.
 5. A self-supporting and portable shield system for protection against blast and ballistic, comprising: a first rigid support frame; one or more armor plates mounted in the first support frame; a second rigid support frame; one or more armor plates mounted in the second support frame; a joint configured to pivotally join the first and second support frames to each other at an edge of the first support frame and an edge of the second support frame; and a connection bar configured to detachably connect the first and second support frames to each other at locations different from locations of the joint; wherein each armor plate is made of materials having blast and/or ballistic resistance properties, and wherein each support frame has a height of 1.7 to 2.0 meters and a width of up to 0.4 meter.
 6. The shield system of claim 5, wherein the joint is removably attached to either or both of the first and second support frames, or the joint includes two parts are assembled together.
 7. The shield system of claim 5, wherein the connection bar is configured to maintain a separation angle between the first and second support frames of 10° to 90°.
 8. The shield system of claim 5, wherein the connection bar is configured to maintain a separation angle between the first and second support frames of 50° to 70°.
 9. The shield system of claim 5, wherein each of the first and second support frames includes one or more horizontal rungs that divide the frame into two or more sections, and each armor plate is located in one of the sections.
 10. The shield system of claim 5, wherein at least one of the first and second support frames includes a horizontal rung near a lower end of the frame. 